Coordination and Response: The Eye
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Questions and Answers

What is the primary function of the cornea in the human eye?

  • Carries impulses to the brain
  • Controls the amount of light entering the eye
  • Focuses light onto the retina
  • Refracts light (correct)

Which part of the eye is responsible for controlling the amount of light that enters?

  • Optic nerve
  • Lens
  • Retina
  • Iris (correct)

What is the role of the optic nerve in the eye?

  • Protects the eye from external damage
  • Focuses light onto the retina
  • Detects color and light
  • Carries impulses to the brain (correct)

Which structure in the retina is known as the point of accurate vision?

<p>Fovea (D)</p> Signup and view all the answers

What is a function of tears produced by the eye?

<p>Reduce friction between the eyelids and the eye (B)</p> Signup and view all the answers

Which of the following describes the pupil reflex?

<p>Changes pupil diameter in response to light intensity (D)</p> Signup and view all the answers

Which part of the eye protects it and is attached to the muscles that move the eye?

<p>Sclera (A)</p> Signup and view all the answers

The area of the retina where the optic nerve and blood vessels exit the eye is known as the:

<p>Blind spot (B)</p> Signup and view all the answers

What causes the blind spot in the eye?

<p>Absence of light receptors (C)</p> Signup and view all the answers

Which fluid helps to maintain the shape of the eye and supports the retina?

<p>Vitreous humour (B)</p> Signup and view all the answers

What happens to the pupil in dim light conditions?

<p>It becomes larger to allow more light in (C)</p> Signup and view all the answers

Where are rod cells primarily located within the eye?

<p>Throughout the entire retina (A)</p> Signup and view all the answers

What triggers the contraction of circular muscles in the iris under bright light conditions?

<p>Contraction of the radial muscles (A)</p> Signup and view all the answers

Which statement correctly describes the function of cone cells?

<p>They are primarily located in the fovea and detect colors (A)</p> Signup and view all the answers

How does the aqueous humor contribute to eye function?

<p>It helps to focus light on the retina (A)</p> Signup and view all the answers

What occurs when looking directly at an object in dim light?

<p>Image clarity is reduced because it falls on the fovea (C)</p> Signup and view all the answers

What is the primary function of insulin in the body?

<p>To decrease blood glucose levels (D)</p> Signup and view all the answers

Which hormone is known as the 'fight or flight' hormone?

<p>Adrenaline (C)</p> Signup and view all the answers

What process is defined as the body's way of maintaining a constant internal environment?

<p>Homeostasis (C)</p> Signup and view all the answers

Which process occurs to help decrease body temperature in hot weather?

<p>Vasodilation (A)</p> Signup and view all the answers

What is the effect of glucagon compared to insulin?

<p>Glucagon increases blood glucose levels, while insulin decreases it (B)</p> Signup and view all the answers

What mechanism does the body use to respond when temperatures rise above normal?

<p>Hypothalamus sends signals to dilate blood vessels. (B)</p> Signup and view all the answers

Which of the following accurately describes the role of hair and fat in thermoregulation?

<p>Both reduce heat loss by acting as insulators. (B)</p> Signup and view all the answers

What is the first step in the negative feedback process for maintaining homeostasis?

<p>A sense organ detects a change. (B)</p> Signup and view all the answers

How does the body respond when it overheats?

<p>Sweat evaporation uses body heat to lower temperature. (A)</p> Signup and view all the answers

What happens to insulin secretion when blood glucose levels return to normal?

<p>Insulin secretion is switched off. (D)</p> Signup and view all the answers

What is the primary role of insulin in the body?

<p>Lower blood glucose levels (A)</p> Signup and view all the answers

Which hormone is secreted when blood glucose levels drop below normal?

<p>Glucagon (B)</p> Signup and view all the answers

How does insulin affect liver cells?

<p>It stimulates the conversion of glucose to glycogen. (B)</p> Signup and view all the answers

What is the function of adrenaline during fight or flight response?

<p>Convert glycogen to glucose (B)</p> Signup and view all the answers

What is the primary cause of Type 1 diabetes?

<p>Body's immune system attacks insulin-producing cells (A)</p> Signup and view all the answers

Which of the following actions does not contribute to the fight or flight response?

<p>Increases rate of digestion (B)</p> Signup and view all the answers

Why can insulin not be taken orally?

<p>It gets broken down by stomach acid (C)</p> Signup and view all the answers

Which of the following is NOT a symptom of diabetes?

<p>Increased hunger (C)</p> Signup and view all the answers

What is one of the primary functions of the kidneys in homeostasis?

<p>Regulate concentration of water and urea (B)</p> Signup and view all the answers

Flashcards

What is the human eye?

A specialized organ in the body that detects and responds to light

What is the Sclera?

The tough, outer layer of the eye that provides protection and is attached to muscles that move the eye.

What is the Cornea?

The transparent front part of the eye, responsible for most of the light refraction.

What is the Iris?

A colored ring around the pupil that controls the amount of light entering the eye.

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What is the Pupil?

The black hole in the center of the eye that allows light to pass through.

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What is the Retina?

The inner lining of the eye containing light receptor cells (rods and cones), which convert light into electrical signals sent to the brain.

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What is the Optic Nerve?

The nerve that carries electrical signals from the retina to the brain, allowing us to see.

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What is the Blind Spot?

The spot on the retina where the optic nerve leaves the eye, lacking light receptors, causing a blind spot.

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How can you locate your blind spot?

To locate your blind spot, hold a book about 50 cm away from your face. Close one eye and focus on a cross on the page. Slowly bring the book closer to your face, and notice how the image of a dot on the page disappears as it falls on your blind spot.

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Why is it harder to see objects in dim light when looking directly at them?

The fovea is a small, central part of the retina that contains only cones, which are responsible for color vision and sharp detail. It is best suited for seeing in bright light. When you look directly at an object in dim light, it falls on the fovea, making it difficult to see. Conversely, if you look slightly to the side, the image falls on the area containing rods, which are sensitive to low light, allowing you to see better in dim conditions.

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What is the vitreous humor?

The vitreous humor is a clear, gel-like substance that fills the space between the lens and the retina. It helps maintain the shape of the eye, support the retina's attachment to the choroid, and refract light to focus it on the retina.

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What is the aqueous humor?

The aqueous humor is a clear fluid that fills the space between the cornea and the lens. It provides nutrients to the lens and cornea, helps to maintain eye pressure, and contributes to light refraction.

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What are hormones?

Hormones are chemical messengers produced by endocrine glands, released directly into the bloodstream, and act on specific target organs or tissues to alter their activity.

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What is insulin?

Insulin is a hormone secreted by the pancreas that helps regulate blood glucose levels by facilitating glucose uptake into cells, lowering blood sugar.

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What is adrenaline?

Adrenaline, also known as epinephrine, is a hormone released in times of stress, preparing the body for "fight or flight" response by increasing heart rate, blood sugar, and alertness.

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What is homeostasis?

Homeostasis is the process of maintaining a stable internal environment within an organism, despite changes in external conditions, by regulating factors like temperature, blood sugar, and pH.

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What is vasodilation?

Vasodilation is the widening of blood vessels, which increases blood flow, helping to cool the body down in hot conditions by releasing heat.

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What is insulin's role in blood sugar regulation?

Insulin is produced by the beta cells in the pancreas. It plays a primary role in regulating blood glucose (sugar) levels, lowering it when it's high. It does this by encouraging cells to take up glucose for energy and stimulating the liver to store excess glucose as glycogen.

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What is adrenaline's purpose?

Adrenaline, also known as epinephrine, acts like a fight-or-flight alarm system. Released by the adrenal glands, it prepares the body for immediate action by increasing heart rate, blood pressure, and breathing rate. It also diverts blood flow to muscles, providing them with extra fuel and oxygen needed for quick responses.

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What is glucagon's role?

Glucagon is a hormone secreted by the alpha cells of the pancreas. It counteracts insulin's effects, raising blood glucose levels when they drop too low. It does this by stimulating the liver to release stored glycogen back into the bloodstream.

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What is diabetes?

Diabetes is a condition where the body's ability to regulate blood glucose is impaired. People with type 1 diabetes cannot produce enough insulin. This can lead to high blood sugar levels (hyperglycemia) or low blood sugar levels (hypoglycemia).

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What is type 1 diabetes?

Type 1 diabetes (also called insulin-dependent diabetes) is an autoimmune disease where the immune system attacks the insulin-producing cells in the pancreas. This means the body can't produce enough insulin to regulate blood sugar.

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Why can't insulin be taken orally?

Insulin cannot be taken orally because it is a protein. It is broken down by digestive enzymes in the stomach and small intestine before it can reach the bloodstream. Therefore, insulin must be injected to enter the bloodstream directly and regulate blood sugar levels.

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What are some symptoms of diabetes?

The symptoms of diabetes include feeling tired, excessively thirsty, frequent urination, and weight loss.

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What are anabolic steroids?

Anabolic steroids are steroid hormones, like testosterone, that stimulate the building of large molecules from smaller ones, such as proteins from amino acids.

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How can anabolic steroids affect athletic performance?

Anabolic steroids can be used to enhance athletic performance by increasing muscle mass and strength, but their use is banned in many competitive sports due to unfair advantage and health risks.

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How is diabetes managed?

Regular blood tests to monitor blood sugar levels, insulin injections, and a carefully regulated diet are essential for managing diabetes.

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How does the hypothalamus regulate body temperature?

The hypothalamus in the brain acts as a temperature sensor. When body temperature rises above normal, it sends signals to decrease temperature. When temperature falls below normal, it sends signals to increase temperature.

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How does the skin respond to over-cooling?

Blood vessels in the skin constrict, reducing blood flow to the surface, decreasing heat loss. Hair erector muscles contract, trapping air for insulation.

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How does the skin respond to over-heating?

Blood vessels in the skin widen, increasing blood flow to the surface, releasing heat. Sweat evaporates, using body heat to cool down.

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What is negative feedback?

Negative feedback is a mechanism for maintaining stable internal conditions by detecting changes, sending signals to correct them, and monitoring the effect of correction.

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How does insulin regulate blood glucose levels?

Insulin is released from the pancreas when blood glucose levels are high, signaling cells to absorb glucose and the liver to store it as glycogen. This lowers blood glucose levels back to normal, reducing insulin release.

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Study Notes

Coordination and Response: The Eye

  • The eye is a sensory organ detecting light.
  • Situated in the orbit (socket) of the skull.
  • Mobile due to three pairs of eye muscles.
  • Protected by the skull, eyelids, eyelashes, and tears.

Components of Tears

  • Water
  • Sodium bicarbonate
  • Sodium Chloride
  • Lysozyme (enzyme)

Functions of Tears

  • Reduces friction between eyelids and eye.
  • Kills microbes using lysozyme.
  • Washes the eye.

Eye Structures and Functions

  • Sclera (Sclerotic coat):
    • Protective muscle fibres attached to eye muscles.
    • Maintains eye shape.
    • Opaque, transparent front part is called the cornea.
  • Cornea:
    • Curved surface, essential for light refraction to enter the eye.
  • Iris:
    • Controls the amount of light entering the pupil.
  • Pupil:
    • Opening in the iris, controls light entry.
  • Lens:
    • Focuses light onto the retina.
  • Retina:
    • Contains light receptors.
    • Some receptors are sensitive to different colours.
    • Contains the fovea and blind spot.
  • Optic nerve:
    • Carries impulses to the brain.
  • Blind spot:
    • Contains no light receptors.
    • Optic nerve and blood vessels leave the eye here.
  • Fovea (yellow spot):
    • High concentration of cones.
    • Point of sharpest vision.
  • Aqueous humor:
    • Saline solution that supports the shape of the eye.
    • Helps refract light.
  • Vitreous humor:
    • Jelly-like fluid that keeps the shape of the eye.
    • Supports the retina.
    • Helps refract light.

How to Locate the Blind Spot

  • Hold a book 50cm from your face.
  • Close one eye, concentrate on a cross.
  • Slowly move the book closer.
  • The cross disappears when it reaches your blind spot.

Pupil Reflex (Dim/Bright Light)

  • Dim light:
    • Radial muscles contract.
    • Circular muscles relax.
    • Pupil widens, letting in more light.
  • Bright light:
    • Radial muscles relax.
    • Circular muscles contract.
    • Pupil narrows to reduce light entry.

Rods and Cones

  • Rods:
    • Numerous, spread throughout the retina (except fovea).
    • Sensitive to low light.
    • Cannot distinguish colours.
    • Have a single type of photoreceptor, responding over a range of light levels.
  • Cones:
    • Fewer in number, concentrated in the fovea.
    • Sensitive to bright light.
    • Detect colours.
    • Three types of photoreceptors (responding to different wavelengths of visible light): red, green & blue.

Near and Far Objects

  • Near object:
    • Ciliary muscles contract.
    • Suspensory ligaments slacken.
    • Lens thickens (accommodation).
    • Pupil narrows.
  • Far object:
    • Ciliary muscles relax.
    • Suspensory ligaments stretch.
    • Lens flattens.
    • Pupil widens.

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Description

Explore the intricate structure and functions of the eye in this quiz on coordination and response. Delve into the role of tears, the components of the eye, and how light is processed to enable vision. Perfect for students studying biology or human anatomy.

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